Reef Formation Research Articles

Carbonate sedimentation on Pacific coral reefs

The contributions in this special issue represent recent advances in carbonate sediment research in and around the coral reefs of the Pacific regions of Japan, New Caledonia, and Tahiti. The issue contains five articles covering a range of subjects including fundamental research on the use corals and large-sized benthic foraminifers in paleoenvironmental reconstructions, facies analyses of modern off-reef sediments, and isotopic analyses of tricanid shells. The issue opens with a classical sedimentary facies description by Yamano et al. (2015), who examine surface carbonate sediments on the outer shelf and slope around New Caledonia. Facies showed significant variations in composition, from benthos- to plankton-dominated, according to water depth, currents, and local seafloor geomorphology. Their results contribute baseline data for examinations of carbonate sedimentary facies in tropical to subtropical environments. Following the description of general facies patterns, the issue contains further investigations on the use of specific organisms (including corals and benthic foraminifers) in reconstructions of facies and paleoenvironments. Humblet et al. (2015) present identification keys for four widespread genera of fossil corals (Acropora, Isopora, Montipora, and Porites) that are commonly recovered from outcrops and drilled cores. They argue that fossil corals should generally be identified from sectioned material, as coral surfaces are usually obscured by encrusters or sediments, and coral specimens are often broken or eroded. Further work extending this type of investigation to all coral genera would greatly contribute to a better understanding of coral reef development and paleoenvironmental assessments. Hongo and Wirrmann (2015) examine cores from Pleistocene and Holocene barrier reefs in New Caledonia and identify several key species for reef formation and maintenance. They emphasize the need for further research on the restoration and conservation of key species, as some of these species are presently in decline. Fujita and Omori (2015) examine large-sized benthic foraminifers from Recent surface sediments and Pleistocene subsurface deposits obtained during Integrated Ocean Drilling Program (IODP) Expedition 310, off Tahiti. By referring to modern foraminifer assemblages, they show that the Pleistocene sequence off Tahiti was deposited in a fore-reef slope environment. As with corals, the authors propose that an examination of modern assemblages of foraminifers would contribute to a better understanding of facies formation and improved paleoenvironmental reconstructions. In addition to their role in sedimentary facies analysis, carbonate skeletons and shells are reliable recorders of paleoenvironments at high temporal resolutions. Asami et al. (2015) present seasonally resolved records of carbon and oxygen isotopic compositions (δ18O) in the fossil shells of giant clams recovered from archeological sites in Okinawa, Japan. Results demonstrate that the annual mean seawater temperature and salinity at Okinawa were approximately 1–3°C higher and 1–2 lower, respectively, at 4000 yr cal. BP and 1900–1700 yr cal. BP than at present; such data provide insights into patterns of human settlement and modes of life in the past. An understanding of facies formation and the reconstruction of paleoenvironments both require process-based analyses. In addition to the five articles mentioned above, Fujita et al. (2015), whose work is to be included in an extended virtual special issue on this topic, examine processes of carbonate sedimentation in seagrass beds in the Ryukyu Islands, Japan. Based on sedimentation rates estimated from coring and sediment influx rates estimated from sediment traps, they identified a sediment-trapping role of seagrass, and characterized the seagrass beds in the Ryukyu Islands as having high sediment fluxes and extremely low sedimentation rates. Collectively, the special issue presents diverse and insightful analyses of Pacific coral reefs. We thank the authors and reviewers who contributed to this issue. Finally, we dedicate this special issue to the memory of our friend and colleague Guy Cabioch (Fig. 1), who sadly passed away in October 2011. All of the senior or corresponding authors, as well as the guest editors, of this special issue collaborated with him. He led many research cruises and drilling programs, and some of the outcomes of his collaborations appear in this special issue. We sincerely thank Guy and pray from the bottom of our hearts that his soul may rest in peace. Guy Cabioch in a research cruise (previous page) and in the field (this page). The photos are provided by Jean-Michel Boré and Denis Wirrmann, respectively.

Preliminary identification of key coral species from New Caledonia (Southwest Pacific Ocean), their significance to reef formation, and responses to environmental change

AbstractThe recognition of key coral species (KCS) in the geological record, i.e. those that contribute to reef formation and maintenance of coral reef ecosystems, is important for understanding the development and evolution of reef ecosystems and for forecasting their responses to climate change and anthropogenic impacts in the near future. This study examined the contribution to reef formation and maintenance of KCS from Pleistocene and Holocene barrier reefs in New Caledonia, based on analyses of six cores retrieved from three different reefs: Islets Kendec, Amédée, and Bayes. Our results indicate that at least 19 genera and 33 species of corals contributed to reef formation and maintenance during the Holocene in New Caledonia. Among them, Goniastrea retiformis, Isopora palifera, Dipsastraea pallida/speciosa complex, corymbose Acropora sp., massive Porites sp., and encrusting Porites sp. were KCS during the Holocene. This observation suggests that KCS will potentially contribute to the formation and persistence of reefs in the near future under conditions of estimated global sea‐level rise of 0.2–0.6 m/100 years. However, the distributions and abundances of these species are currently decreasing. This study emphasizes the need for further research on the restoration and conservation of potential KCS.

Codition of Coral Reef at Teluk Pandan Sub-District East Kutai District

Coral reef of TelukPandan Sub-district East Kutai District still low in both monitoring and management, thus also poorly in coral reef database. This research purpose was to obtain the data of coral reef condition and distribution description in this sub-district. Research was held on October 2013 at six observation stations using lifeform line intercept transect survey method. The coral condition estimation was based on live coral cover (LC) and hard coral mortality index (HCM). Coral reef distribution and wide were estimated by satellite image Landsat 7 ETM+ processing and direct field tracking using GPS. There estimated ± 618.63 ha of coral reef area consist of fringing and patch reef formation type. Live coral cover vary 2.1-67.8% or categorized “poor” to “good” reef condition and in average LC = 38.1% (“fair/moderate” condition). Hard coral morality (HCM) index ranged 0.14 – 0.8 and in average 0.31.

Quantifying the relative importance of transcellular and paracellular ion transports to coral polyp calcification

Ocean acidification due to rising atmospheric pCO2 slows down coral calcification and impedes reef formation, with deleterious consequences for the diversity of reef ecosystems. Such interactions contrast with the capacity of corals to actively regulate the chemical composition of the calcifying fluid where calcification occurs. This regulation involves the active transport of calcium, bicarbonate, and hydrogen ions through epithelium cells, the transcellular pathway. Ions can also passively diffuse through intercellular spaces via the paracellular pathway, which directly exposes the calcifying fluid to changes in ocean chemistry. Although evidence exists for both pathways, their relative contribution to coral calcification remains unknown. Here we use a mathematical model to test the plausibility of different calcification mechanisms also in relation to ocean acidification. We find that the paracellular pathway generates an efflux of calcium and carbonate from the calcifying fluid, causing a leakage of ions that counteracts the concentration gradients maintained by the transcellular pathway. Increasing ocean acidity exacerbates this carbonate leakage and reduces the ability of corals to accrete calcium carbonate.

Seismic Profile Characteristics of Reefs and Hydrocarbon Detection Technology in Northwest Palawan Basin

In the hanging wall of faults which controlled the Paleocene depression in the Northwest Palawan Basin in the South China Sea, a large number of ancient terrain height reefs and thick mudstones are well developed, forming important reservoir cap combination type in the study area. Through years of exploration and development, 27 reef oil and gas fields have been discovered. In this article, the Northwest Palawan basin evolution and reef formation in this basin have been discussed, and the seismic response characteristics of reef oil and gas reservoir discovered in this basin are summarized, which lay a solid foundation for valid identification of reef reservoirs. Meanwhile, the reef reservoirs after containing oil and gas are characterized by high impedance and lowfrequency. The sparse spike inversion method and filtering method by setting threshold value of seismic attribute have been used to detect hydrocarbon bearing conditions of reefs to improve the reef reservoir exploration success rate.

Chapter 15 The rock coasts of oceanic islands

Abstract Oceanic plates are geologically young, forming at mid-ocean ridges and becoming deeper and older with distance away from these spreading centres, to be subducted into ocean trenches. Most of the islands that occur on these oceanic plates are basaltic, formed at hot spots, and carried into deeper water as the plate migrates. In tropical reef-forming seas, volcanic islands are usually protected by coral reefs, and undergo transition from fringing reefs, to barrier reefs, to atolls, as envisaged by Darwin. Linear island chains comprise volcanic islands at successive stages in the progression from volcano through coral reefs to seamounts and guyots. Erosion occurs rapidly in the early stages once eruption has ceased, and older islands are conspicuously dissected by fluvial action, as observed by Dana. Many are subject to submarine slumping. In the absence of coral reefs, marine abrasion truncates islands, producing near-vertical cliffs, and islands may be entirely bevelled; Balls Pyramid in the southern Pacific appears to be at the penultimate stage of this planation with a broad shelf around it. Coral reefs protect the shoreline, which is usually deeply embayed, with progressive subsidence until volcanic residuals are all that remain on ‘almost-atolls’. Reef limestones indicate earlier phases of reef formation, and there are limestone cliffs around many tropical islands composed of Last Interglacial limestone often veneering older reef terraces. In some cases, the morphology of these limestone coasts contains prominent notches or surf benches reflecting different degrees of exposure to wave energy, or subtle flexure and vertical displacement. Islands provide discrete examples of rocky coasts, with contrasts between adjacent islands, or islands of different ages, providing many insights into the evolutionary stages and the morphodynamics of bold coasts.

Feature selection in wind speed prediction systems based on a hybrid coral reefs optimization – Extreme learning machine approach

This paper presents a novel approach for short-term wind speed prediction based on a Coral Reefs Optimization algorithm (CRO) and an Extreme Learning Machine (ELM), using meteorological predictive variables from a physical model (the Weather Research and Forecast model, WRF). The approach is based on a Feature Selection Problem (FSP) carried out with the CRO, that must obtain a reduced number of predictive variables out of the total available from the WRF. This set of features will be the input of an ELM, that finally provides the wind speed prediction. The CRO is a novel bio-inspired approach, based on the simulation of reef formation and coral reproduction, able to obtain excellent results in optimization problems. On the other hand, the ELM is a new paradigm in neural networks’ training, that provides a robust and extremely fast training of the network. Together, these algorithms are able to successfully solve this problem of feature selection in short-term wind speed prediction. Experiments in a real wind farm in the USA show the excellent performance of the CRO–ELM approach in this FSP wind speed prediction problem.

Millennial-scale ocean acidification and late Quaternary decline of cryptic bacterial crusts in tropical reefs.

Ocean acidification by atmospheric carbon dioxide has increased almost continuously since the last glacial maximum (LGM), 21,000 years ago. It is expected to impair tropical reef development, but effects on reefs at the present day and in the recent past have proved difficult to evaluate. We present evidence that acidification has already significantly reduced the formation of calcified bacterial crusts in tropical reefs. Unlike major reef builders such as coralline algae and corals that more closely control their calcification, bacterial calcification is very sensitive to ambient changes in carbonate chemistry. Bacterial crusts in reef cavities have declined in thickness over the past 14,000 years with largest reduction occurring 12,000-10,000 years ago. We interpret this as an early effect of deglacial ocean acidification on reef calcification and infer that similar crusts were likely to have been thicker when seawater carbonate saturation was increased during earlier glacial intervals, and thinner during interglacials. These changes in crust thickness could have substantially affected reef development over glacial cycles, as rigid crusts significantly strengthen framework and their reduction would have increased the susceptibility of reefs to biological and physical erosion. Bacterial crust decline reveals previously unrecognized millennial-scale acidification effects on tropical reefs. This directs attention to the role of crusts in reef formation and the ability of bioinduced calcification to reflect changes in seawater chemistry. It also provides a long-term context for assessing anticipated anthropogenic effects.

Wet season upwelling and dry season chlorophyll-a describe interannual growth rates of Porites in southern China.

Southern China hosts coral communities in marginal environments that are characterized by low linear extension rates, low coral cover and/or no reef formation, thus providing natural laboratories to study coral communities with below average growth rates. Here we compare the annual linear extension rates over 10 years (range 1.2 to 11.4 mm yr−1) of six Porites sp. coral cores collected from Hong Kong with monthly hydrographic data from the Hong Kong Environmental Protection Department. At all sites, low-density, dry season extension were more variable than high-density, wet season extension and on average, was lower at two of the three sites. We applied multi-variate linear regressions that revealed high-density, wet season band extension to inversely correlate most significantly to temperature (r = −0.39, p<0.01). In contrast, low-density, dry season band extension was more variable and correlated most significantly with dry season chlorophyll-a (Chl-a) (r = 0.64, p<0.001). Additionally, we find that corals at the site with highest dry season Chl-a have the highest dry season extension lengths. Our findings indicate that relative mixing of fresh and salt water in the wet season and primary productivity in the dry season, and their influences on aragonite saturation, are likely to impact interannual coral extension variability in marginal environments.

An early Middle Anisian (Middle Triassic) Tubiphytes and cement crusts-dominated reef from North Dobrogea (Romania): facies, depositional environment and diagenesis

Abstract A well-developed Triassic carbonate platform is exposed in the eastern part of the Tulcea Unit, in the Cimmerian North Dobrogean Orogen, southeastern Romania. Facies analysis of the 200 m thick succession of lower Middle Anisian limestones exposed in a large limestone quarry south of the village of Mahmudia suggests a transition from upper slope towards toe-of-slope carbonate facies, reflecting sea-level fluctuations and tectonic tilting. The slope is dominated by in situ microbialites in the upper portion, consisting of reefal boundstone facies, and by molluscan coquina and cement boundstones. A key role is played by the cosmopolitan micro-encruster Tubiphytes, which became common in the aftermath of the mass extinction at the Permian/Triassic boundary, and by autochthonous micrite and synsedimentary marine cement. The absence of metazoan reef builders, such as sponges and corals, reflects the fact that microbes were the first organisms to recover after the Permian/Triassic crisis under unusual marine conditions and that their main role in reef formation was sediment stabilization along the upper slopes. The lower slope is mostly detrital, being dominated by platform-derived bioclastic rudstones and crinoidal floatstones, which are interbedded with basinal carbonate hemipelagics. The toe-of-slope is composed of pelagic wackestones framed by thin tongues of intraclast breccia. All these observations are in agreement with the slopeshedding model described for the Pennsylvanian microbial margin in Asturias (northern Spain) and the Anisian- Ladinian flat-topped, steep-rimmed Latemar platform (Dolomites, Italy). As most of the Anisian reefs were described from western and eastern Tethys (Southern Alps, Hungary, China), the occurrence of the early Middle Anisian Tubiphytes-reef from North Dobrogea (Romania) contributes to resolving the puzzle of the geographic distribution of reef recovery in the Middle Triassic.

Coral calcification under daily oxygen saturation and pH dynamics reveals the important role of oxygen

ABSTRACTCoral reefs are essential to many nations, and are currently in global decline. Although climate models predict decreases in seawater pH (∼0.3 units) and oxygen saturation (∼5 percentage points), these are exceeded by the current daily pH and oxygen fluctuations on many reefs (pH 7.8–8.7 and 27–241% O2 saturation). We investigated the effect of oxygen and pH fluctuations on coral calcification in the laboratory using the model species Acropora millepora. Light calcification rates were greatly enhanced (+178%) by increased seawater pH, but only at normoxia; hyperoxia completely negated this positive effect. Dark calcification rates were significantly inhibited (51–75%) at hypoxia, whereas pH had no effect. Our preliminary results suggest that within the current oxygen and pH range, oxygen has substantial control over coral growth, whereas the role of pH is limited. This has implications for reef formation in this era of rapid climate change, which is accompanied by a decrease in seawater oxygen saturation owing to higher water temperatures and coastal eutrophication.

Diversidad y abundancia relativa de corales, octocorales y esponjas en el Parque Nacional Jaragua, República Dominicana

The Jaragua National Park is located in a remote area to the SW coast of the Dominican Republic. Fishing and mining are the major human activities. The main reef formations of the Park include: (a) long bank reefs (spur and groove) growing as bands over the platform and running in a SW-NW direction at 12-25 m depth, (b) well developed, deep, fringing reefs at the platform edge (drop-off) areas which could extend from 10 to 45 m depth, and (c) small patch reefs and poorly developed coral-octocoral-sponge-algal communities in shallow platforms near shore, rocky bottoms, and over the submerged walls of the uplifted reef. Nine reef localities were surveyed between Cabo Beata and Bahia Honda using Scuba diving to inventory the diversity and relative abundance of scleractinian corals, octocorals and sponges. Fringing reefs were surveyed starting at the bottom (30 m) and swimming in a zig-zag pattern (50 m on each side) to shallower areas. Bank reefs were surveyed by swimming in zig-zag across the spur-groove formation along 500 m. Sponges were the most diverse group with 83 species in 50 genera followed by the scleractinian corals with 56 species in 26 genera and the octocorals with 47 species in 15 genera. New records included eight coral species, 29 octocoral species and 59 sponges. The diversity, species composition and abundance of particular groups varied across the different localities. Northern reefs within the park and the Los Frailes Island offshore had the highest live cover, relative abundance and diversity for the three groups. In general, the Jaragua National Park had the highest diversity of corals, octocorals and sponges reported for the Dominican Republic and rank amongst the highest reported for the northern Caribbean. It is recommended that the area be protected and that fishing activities be regulated or eliminated altogether.

Eastern oysters Crassostrea virginica deter crab predators by altering their morphology in response to crab cues

Many prey species alter their behavior and/or morphology in response to exudates from predators and injured con- or heterospecifics to alleviate predation risk. Yet, few studies have assessed the effectiveness of risk aversion in prey in terms of decreasing mortality. Recent studies have shown that eastern oysters Crassostrea virginica produce heavier shells in the pres- ence of predators, but the benefits of this morphological change have not been evaluated. We per- formed an indoor laboratory experiment and exposed newly settled oysters to chemical cues from 2 common predators: blue crabs Callinectes sapidus and Atlantic mud crabs Panopeus herbstii. After 8 wk, we compared shell diameter, shell mass, shell breaking force, and susceptibility to pre- dation between juvenile oysters in these predator treatments to those in controls without preda- tors. Oyster shell diameter and mass were significantly greater in blue crab treatments than in controls, and mud crabs and controls were not significantly different in these parameters. Yet, in both mud crab and blue crab treatments, oysters produced shells that required more force to crush as measured with a hand-held force transducer. Oysters reared in the presence of blue and mud crabs were less susceptible to predation than those maintained in no-predator controls in feeding assays performed after the 8 wk induction. Although oysters reacted differently to mud crabs and blue crabs, changing their shell morphology was an effective deterrent against predators. Future studies are needed to determine the long-term effects of induced responses to predators on oyster growth, fitness, and reef formation.

Evolutionary history of pentamerids (Brachiopoda) in the Timan-North Ural Basin

Evolutionary history of Early Paleozoic pentamerids, which first appeared in the Late Ordovician and existed until the Early Devonian in the Timan-North Ural Basin is closely related to changes in sedimentation conditions, processes of the reef formation, and considerable rearrangements in marine ecosystems. Several parallel pentamerid communities similar in ecology and morphology are recognized.

Evidence of photosymbiosis in Palaeozoic tabulate corals

Coral reefs form the most diverse of all marine ecosystems on the Earth. Corals are among their main components and owe their bioconstructing abilities to a symbiosis with algae (Symbiodinium). The coral-algae symbiosis had been traced back to the Triassic (ca 240 Ma). Modern reef-building corals (Scleractinia) appeared after the Permian-Triassic crisis; in the Palaeozoic, some of the main reef constructors were extinct tabulate corals. The calcium carbonate secreted by extant photosymbiotic corals bears characteristic isotope (C and O) signatures. The analysis of tabulate corals belonging to four orders (Favositida, Heliolitida, Syringoporida and Auloporida) from Silurian to Permian strata of Europe and Africa shows these characteristic carbon and oxygen stable isotope signatures. The δ(18)O to δ(13)C ratios in recent photosymbiotic scleractinians are very similar to those of Palaeozoic tabulates, thus providing strong evidence of such symbioses as early as the Middle Silurian (ca 430 Ma). Corals in Palaeozoic reefs used the same cellular mechanisms for carbonate secretion as recent reefs, and thus contributed to reef formation.

BECOMING JOHN UPDIKE: CRITICAL RECEPTION, 1958–2010

BECOMING JOHN UPDIKE: CRITICAL RECEPTION, 1958-2010. By Laurence W. Mazzeno. Rochester, NY: Camden House, 2013. $85.In an interview, "At Home with John Updike," that aired on WGBH TV on July 28, 1978, John Updike (1932-2009) suggested an analogy between the process of writing and the formation of coral reefs and snowfall. Accumulation is slow for each, but with a steady output over considerable time, the resulting yield can be truly substantial. This is apparent when considering Updike's oeuvre as well as its critical reception. For more than a half century, it has been snowing Updike, to the point that we now have an immense accumulation: Updike published more than sixty books; reviewers and critics have responded with forty full-length volumes, hundreds of articles, and thousands of book reviews (In the Beauty of the Lilies [1996] alone received two hundred reviews). Getting one's arms around Updike, then, is no small task, which is why Updike scholarship owes a debt to Laurence W. Mazzeno. Although not an Updike scholar, Mazzeno, the author of several works on Victorian literature and president emeritus of Alvernia University, located in the city of Updike's birth (Reading, Pennsylvania), has sifted through that writing to produce a clear, well-organized, and useful reference work.Becoming John Updike comprises ten chronological chapters, each of which covers about five years of criticism. The fifth chapter, spanning 1986 to 1990, devotes fifteen pages to summarizing book reviews of Roger's Version (1986), Trust Me (1987), S. (1988), Self-Consciousness (1989), Just Looking (1989), and Rabbit at Rest (1990) (one to four pages for each), then concludes with a nine-page summary of academic criticism published during that same period. The volume, Mazzeno explains, is designed "to trace the growth of Updike's reputation and examine the reasons for his success" (3).The word Becoming in the title is instructive and sheds light on why the volume does not, as it easily could, become tedious; reading sixty consecutive summaries of book reviews could, potentially, be lethal. Mazzeno keeps his narrative interesting by charting, through a half century of critical writings, "how [Updike] 'became' the 'John Updike' that, at his death, was almost universally hailed as a major voice in American literature" (3). Although similarities exist between Updike's early and later work (attention to the quotidian, a lushly eloquent style, etc.), Mazzeno makes it clear that Updike's fiction, essays, and poetry evolved. We may think that works such as Couples (1968), The Coup (1978), Rabbit Is Rich (1981), Hugging the Shore (1983), The Witches of Eastwick (1984), and Rabbit at Rest were inevitable, yet any reader of Updike's early work could hardly have predicted these volumes. Clearly, Updike's subject matter and thematic interests, like his prose style, developed and matured. While isolating a single factor behind these changes is challenging, Mazzeno suggests that "Updike engaged in dialogue with reviewers and academic critics" (2-3) to the degree that their writing played a role, perhaps, in his decision to step out of familiar territory, a decision that may have led him to write about Africa in The Coup and to inhabit a female perspective in The Witches of Eastwick.Mazzeno makes two important points early on that guide his study. The first point is that "Updike had the distinction of being reviewed early and often" (6). Unlike such contemporaries as Don DeLillo and Cormac McCarthy, Updike was closely watched from his early twenties until his death at seventy-six. The second point is that, throughout his career, "Updike was a controversial figure in American letters: for some a major voice in fiction, for others a pretentious mannerist who substituted florid stylistic flourishes for substantive insight" (1). Updike's first novel, The Poorhouse Fair (1959), highlights both points. Unusual, at least for a first novel, in its subject matter (a home for the elderly), it appeared briefly on the New York Times best-seller list and was reviewed widely. …

Mid-Holocene sea-level and coral reef demise: U-Th dating of subfossil corals in Moreton Bay, Australia

It is increasingly apparent that sea-level data (e.g. microfossil transfer functions, dated coral microatolls and direct observations from satellite and tidal gauges) vary temporally and spatially at regional to local scales, thus limiting our ability to model future sea-level rise for many regions. Understanding sea-level response at ‘far-field’ locations at regional scales is fundamental for formulating more relevant sea-level rise susceptibility models within these regions under future global change projections. Fossil corals and reefs in particular are valuable tools for reconstructing past sea levels and possible environmental phase shifts beyond the temporal constraints of instrumental records. This study used abundant surface geochronological data based on in situ subfossil corals and precise elevation surveys to determine previous sea level in Moreton Bay, eastern Australia, a far-field site. A total of 64 U-Th dates show that relative sea level was at least 1.1 m above modern lowest astronomical tide (LAT) from at least ~6600 cal. yr BP. Furthermore, a rapid synchronous demise in coral reef growth occurred in Moreton Bay ~5800 cal. yr BP, coinciding with reported reef hiatus periods in other areas around the Indo-Pacific region. Evaluating past reef growth patterns and phases allows for a better interpretation of anthropogenic forcing versus natural environmental/climatic cycles that effect reef formation and demise at all scales and may allow better prediction of reef response to future global change.

Offshore wind farm design with the Coral Reefs Optimization algorithm

This paper presents a novel algorithm for wind farm design and layout optimization: the Coral Reefs Optimization algorithm (CRO). The CRO is a novel bio-inspired approach, based on the simulation of reef formation and coral reproduction. The CRO is fully described and detailed in this paper, and then applied to the design of a real offshore wind farm in northern Europe. It is shown that the CRO outperforms the results of alternative algorithms in this problem, such as Evolutionary Approaches, Differential Evolution or Harmony Search algorithms.

Discussion of “The Bushveld Complex, South Africa: formation of platinum–palladium, chrome- and vanadium-rich layers via hydrodynamic sorting of a mobilized cumulate slurry in a large, relatively slowly cooling, subsiding magma chamber” by Maier et al. (2013) Miner Deposita 48:1–56

We believe the hypothesis presented by Maier et al. (Miner Deposita 48:1–56, 2012) for the formation of the various ore bodies in the Bushveld Complex to be overly simplistic, and we raise concerns that some of our work, used in support of this hypothesis, has been misrepresented. The formation of both diverse metalliferous layers (platinum-group element (PGE) reefs and Ti-magnetite layers) and some discordant (pipe) ore deposits has been ascribed by Maier et al. to the single unifying process of hydrodynamic sorting. The problem faced by authors of universal hypotheses for the Bushveld Complex is the sheer size and complexity of the intrusion. We disagree with many aspects of the overall Maier et al. model and have also identified several minor errors on maps and photographs, although some of these do not have a material effect on the model. The nature and origin of the layering is, however, too complex a topic to deal with in the context of this commentary, and we restrict ourselves to noting that our preferred hypothesis, namely the incremental buildup of layering from numerous episodes of replenishment, by different magma lineages, is consistent with field relationships. Our hypothesis for the origin of the ultramafic-hosted PGE-rich reefs, i.e., lateral mixing, is applicable to economically mineralized reefs (Mitchell and Scoon, Econ Geol 102:971–1009, 2007) and poorly mineralized layers such as the Pseudoreef harzburgite (Scoon and De Klerk, Canad Mineral 25:51–77, 1987) and the chromitite layers below the UG2 (Scoon and Teigler, Econ Geol 89:1094–1121, 1994).

Geochemical and physical constraints for the occurrence of living cold-water corals

Cold-water coral communities cover a wide range of possible habitats in terms of latitude, ocean basins, and depth, with ongoing studies continually expanding occurrences in various regions of the global ocean. A range of factors determines the formation of cold-water coral reefs, such as physical, hydrochemical, and biological (e.g. food supply) factors. Recently, more and more modeling studies have emerged using a variety of mathematical approaches have emerged including environmental niche factor analysis (ENFA) and predictive habitat suitability models. However, only few studies have attempted to characterize the underlying suite of hydro-biogeochemical and physical constraints of cold-water coral reefs and to differentiate between pristine reef growth vs. sites with reduced or no coral occurrences. This study concentrates on new data and a compilation of existing data sets on the physical and chemical properties in the NE Atlantic and the Mediterranean. It explores the influence of ambient bottom waters and its characteristics on living cold-water reefs and mounds formed by Lophelia pertusa. Several questions are addressed: (1) what are the physical and geochemical boundary conditions of living cold-water corals? (2) Do these geochemical parameters correlate with proposed physical prerequisites? (3) Is there a general difference in the signature of living and dead coral sites?